This invention relates to a liquid chromatography in which concentrations of components contained in a solution to be introduced into a separation column are elevated before the introduction of the solution into the separation column, and an apparatus for carrying out the liquid chromatography.
In liquid chromatography, a dilute sample solution containing only a very small amount of components to be measured must be often subjected to the measurement. Therefore, it is an indispensable condition to increase the sensitivity of a detector, but even if a measuring apparatus with the highest sensitivity is used, there still are components at a concentration too low to measure the components. In that case, it is effective to concentrate a sample in advance. According to the conventional procedure, the dilute sample components are concentrated in advance by evaporation or solvent extraction, but these concentrating operations are carried out with equipment or device or special reagents having nothing to do with the apparatus for liquid chromatography. Therefore, there are so many changes for errors of measurement.
Furthermore, the concentration based on the evaporation or solvent extraction generally requires much time, and complicates operations. It takes a few minutes to several tens of minutes in the chromatographic separation and detection according to an apparatus for liquid chromatography, but it takes much more time in the concentration as a pretreatment for the chromatography than in the chromatographic separation and detection. Thus, the feature or capacity of the apparatus for liquid chromatography cannot be fully attained. Furthermore, the evaporation and solvent extraction require much labor.
In the measurement, it should be taken into consideration that, as soon as a solution containing components to be measured reaches a separation column, the separation starts to take place. When a large amount of a solution must be introduced into the separation column, that is, it takes much time in the introduction into the separation column, it will be difficult to separate the components from one another. Therefore, it must be avoided to introduce a large amount of the solution to the separation column.